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Timelines – Human Brain

First Milestone – Inception in Primate Ancestors (around 55-60 million years ago): The development of the primate lineage from pre-primate mammals marks the inception of the human brain. The primitive brain at this stage comprised a small walnut-like organ featuring basic parts such as the cerebrum and the brainstem for regulating primal survival, metabolic processes, and behaviors.

Second Milestone – Enlargement of the Primate Brain (around 20-25 million years ago): Between the Miocene and Pliocene epochs, there was a considerable enlargement in the primate brain’s size. “Encephalization,” or the increase in brain size relative to body size, was observed. The cerebral cortex started expanding, allowing for the development of advanced cognitive capacities like problem-solving and communication.

Third Milestone – Hominid Brain Expansion (around 5-7 million years ago): This stage marks the evolution of hominids, our early bipedal relatives. The brain size increased further (reaching around 500-600 cubic centimeters), possibly due to genetic mutations and environmental demands. Features like a distinguished prefrontal cortex began to emerge, which is associated with complex decision-making and social interactions.

Fourth Milestone – Emergence of Homo Sapiens (around 200,000-300,000 years ago): Following the emergence of the Homo (man) genus, Homo sapiens evolved with a significant increase in brain size, about 1350-1500 cubic centimeters, akin to present-day humans. This growth facilitated an unprecedented universality of capabilities like abstract thinking, problem-solving, language, and culture.

Fifth Milestone – Cognitive Revolution (around 70,000 years ago): This phase is characterized by the Cognitive Revolution wherein Homo sapiens began to exhibit behaviors attributed to symbolic thought, such as creating art and engaging in religious rituals. Concomitant brain developments might have included enhancement of language-encoding structures and higher cognitive process areas like the prefrontal cortex.

Sixth Milestone – The Neolithic Revolution(around 10,000 years ago): The advent of agriculture and domestication of animals involved further fine-tuning of the human cortex. The need for planned cultivation, animal rearing, social organization, storage, and distribution of food surpluses required the development of advanced cognitive functions and memory processing.

Seventh Milestone – Modern Brain (Present): The human brain today, while physically comparable to our ancient ancestors’, operates in an entirely different sociocultural context and technological landscape. Hence, contemporary selection pressures, such as digital technology, are now inciting a minor reorganization of some functional capacities, like multitasking efficiency and information processing speed.